Answer
$\dfrac{172,704}{5,632,705}\sqrt 2(1-e^{-14\pi})$
Work Step by Step
Here, we have $ds=\sqrt{(dx/dt)^2+(dy/dt)^2+(dz/dt)^2}$
This implies that $ds=\sqrt{(-e^{-t}\cos 4t-4e^{-t} \sin 4t)^2+(-e^{-t}\sin 4t-4e^{-t} \cos 4t)^2+(-e^{-t})^2}dt=e^{-t} \sqrt {18} dt$
Now, we have $\int_{C} x^2y^2zds=\int_{0}^{2 \pi} (-e^{-t}\cos 4t)^3 \cdot (e^{-t} \sqrt {18} dt)$
When we use calculator, then we have $\int_{C} x^2y^2zds=\dfrac{172,704}{5,632,705}\sqrt 2(1-e^{-14\pi})$
